CN102768952A - Method for reprocessing unqualified monocrystalline silicon wafers after diffusion - Google Patents

Method for reprocessing unqualified monocrystalline silicon wafers after diffusion Download PDF

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CN102768952A
CN102768952A CN201210271684XA CN201210271684A CN102768952A CN 102768952 A CN102768952 A CN 102768952A CN 201210271684X A CN201210271684X A CN 201210271684XA CN 201210271684 A CN201210271684 A CN 201210271684A CN 102768952 A CN102768952 A CN 102768952A
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diffusion
solution
substandard products
silicon chip
monocrystalline silicon
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CN102768952B (en
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吴艳芬
詹国平
陈筑
刘晓巍
刘伟
徐晓群
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Ningbo Eureka solar energy Co., Ltd
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NINGBO ULICA SOLAR TECHNOLOGY DEVELOPMENT Co Ltd
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Abstract

The invention discloses a method for reprocessing unqualified monocrystalline silicon wafers after diffusion, comprising the following steps: placing and soaking diffused unqualified products into a hydrofluoric acid solution for 4-10 minutes to eliminate phosphorosilicate glass layers formed during the diffusion process, wherein the volume ratio of hydrofluoric acids to water in the hydrofluoric acid solution is 1:(4-10); washing the processed unqualified silicon wafers with deionized water to eliminate the hydrofluoric acids remaining on the surfaces of the silicon wafers; placing and soaking the processed silicon wafers in a hot NaOH solution for 2-5 minutes to eliminate diffusion layers on the surfaces of silicon, wherein the mass concentration of the NaOH solution is 2%-10%, and the temperature of the NaOH solution is 60-80 DEG C; and washing the silicon wafers with an H2O2 solution, wherein the volume ratio of H2O2 to water in the H2O2 solution is 1:(4-10). The method provided by the invention has the advantages of reducing the production cost and improving the qualified rate of cells.

Description

Diffusion back monocrystalline silicon piece substandard products reworking method
Technical field:
The invention belongs to crystal silicon solar energy battery and make the field, be specially a kind of diffusion back monocrystalline silicon piece substandard products reworking method.
Background technology:
Diffusion is the critical process in the solar cell manufacturing process, and purpose is to utilize POCl3 (POCl 3) doping of at high temperature carrying out phosphorus atoms makes PN junction, its process is following:
POCl 3(> at high temperature; 600 ℃) decomposition generation phosphorus pentachloride (PCl 5) and phosphorus pentoxide (P 2O 5), its reaction equation is following:
5POCl 3→3PCl 5+P 2O 5
In diffusion atmosphere, usually be connected with a certain amount of oxygen, can make the PCl of generation 5Further decompose, make phosphorus pentachloride be oxidized to P 2O 5Thereby, can obtain more phosphorus atoms and be deposited on the silicon chip surface.Also can avoid PC1 in addition 3To the corrosiveness of silicon chip, can improve silicon chip surface, reaction equation is following:
4PCl 5+5O 2→2P 2O 5+10Cl 2
The P that generates 2O 5One-tenth continues to obtain phosphorus atoms with pasc reaction under diffusion temperature, and its reaction equation is following
2P 2O 5+5Si→5SiO 2+4P↓
So far diffusion process finishes, the phosphorus atoms that in apart from the thickness of silicon chip surface 0.3-0.5um, mixes, and this layer is called diffusion layer, on silicon chip surface, forms the SiO that one deck contains P elements simultaneously 2, be called phosphorosilicate glass.
Method for supervising to diffusing procedure is a square resistance of taking a sample test diffusion back silicon chip, if exceed predefined scope, then belongs to substandard products.Because of square resistance receives the influence of many factors such as sour discharge capacity in POCl3 liquid level, the boiler tube in source bottle temperature, furnace tube temperature, the source bottle, so the underproof situation of square resistance is more frequent.If continuing to make battery, such substandard products can produce a large amount of efficiency battery sheets.
Be such to the processing of doing over again of spreading back silicon chip substandard products at present: the excessive silicon chip of square resistance is reentered into and carries out the secondary diffusion in the diffusion furnace; But the difficult control square resistance of this method; Be easy to generate repeatedly and do over again, not only influence output but also influence the battery qualification rate.The no better treating method that square resistance is too small is generally directly scrapped or is made battery, can increase production cost but directly scrap, and directly makes battery and will produce a large amount of efficiency battery sheets, also can cause the reduction of battery qualification rate.
Summary of the invention:
The present invention is directed to the above-mentioned deficiency of prior art, a kind of easy control square resistance is provided, need not repeatedly to do over again, can reduce production costs, monocrystalline silicon piece substandard products reworking method after the diffusion of raising battery qualification rate.
In order to solve the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of diffusion back monocrystalline silicon piece substandard products reworking method may further comprise the steps:
(1) the substandard products silicon chip after will spreading is put into hydrofluoric acid solution and is soaked 4~10min, removes the phosphorosilicate glass layer that forms in the diffusion process, and wherein the volume ratio of hydrofluoric acid and water is 1:4~10 in the hydrofluoric acid solution;
(2) silicon chip after step (1) immersion is used washed with de-ionized water, remove the residual hydrofluoric acid of silicon chip surface;
(3) silicon chip after step (2) cleaning is put into NaOH solution and soak 2min~5min, wherein the mass percent concentration of NaOH solution is 2%~10%, and the temperature of NaOH solution is 60 ℃~80 ℃, to remove the surface diffusion layer of silicon;
(4) silicon chip after step (3) immersion is used H 2O 2Solution cleans up silicon chip, H 2O 2H in the solution 2O 2With the volume ratio of water be 1:4~10.
As preferably, the volume ratio of HF and water is 1:5 in step (1) hydrofluoric acid solution.
As preferably, the soak time in the step (1) is 6min.
As preferably, the mass concentration of NaOH solution is 5% in the step (3).
As preferably, the temperature of NaOH solution is 80 ℃ in the step (3).
As preferably, soak time is 2.5min in the step (3).
As preferably, step (4) H 2O 2H in the solution 2O 2With the volume ratio of water be 1:6.
Advantage of the present invention and beneficial effect: adopt method of the present invention; Can so that the phosphorosilicate glass layer of silicon chip surface and diffusion layer removed fully, with normal silicon chip indifference, thus manufacture batteries sheet again; Reduce production cost, improved the battery qualification rate.
Description of drawings
Fig. 1 is the preceding silicon chip structural representation of diffusion.
Fig. 2 is diffusion back silicon chip structural representation.
Wherein: 1. silicon chip, 2. diffusion layer, 3. phosphorosilicate glass.
Embodiment
Through embodiment the present invention is described in further detail below, but the present invention not only is confined to following examples.
Embodiment 1
Pre-configured HF solution, wherein the volume ratio of HF and water is 1:5; Configuration concentration is 5% NaOH solution and is heated to 80 ℃ then, disposes H at last 2O 2Solution, wherein H 2O 2With the volume ratio of water be 1:6.
The first step: will spread back square resistance unusual monocrystalline silicon piece substandard products (as shown in Figure 2, the silicon chip substandard products structure after the diffusion: comprise silicon chip 1, diffusion layer 2 and phosphorosilicate glass 3) and put into HF solution and soak 6min.
Second step: just the monocrystalline silicon piece tank of putting into deionized water soaks, and with deionized water residual HF solution on the silicon chip is cleaned up, and test water quality be neutrality until pH.
The 3rd step: NaOH solution is put in the silicon chip taking-up that will clean later, soaks 2.5min, and the diffusion layer on surface is removed.
The 4th step: silicon chip is placed H 2O 2During solution is incited somebody to action, the metal ion of removing surface irregularities and possibly existing.
The silicon chip that cleans up is (structure is as shown in Figure 1, and one deck silicon chip 1 structure is only arranged) after super-dry, and first procedure of making from battery begins manufacture batteries again.
Embodiment 2
Pre-configured HF solution, wherein the volume ratio of HF and water is 1:6; Configuration concentration is 6% NaOH solution and is heated to 70 ℃ then, disposes H at last 2O 2Solution, wherein H 2O 2With the volume ratio of water be 1:6.
The first step: will spread back square resistance unusual monocrystalline silicon piece substandard products and put into HF solution and soak 6min.
Second step: just the monocrystalline silicon piece tank of putting into deionized water soaks, and with deionized water residual HF solution on the silicon chip is cleaned up, and test water quality be neutrality until pH.
The 3rd step: NaOH solution is put in the silicon chip taking-up that will clean later, soaks 3min, and the diffusion layer on surface is removed.
The 4th step: silicon chip is placed H 2O 2During solution is incited somebody to action, the metal ion of removing surface irregularities and possibly existing.
The silicon chip that cleans up is after super-dry, and first procedure of making from battery begins manufacture batteries again.

Claims (7)

1. monocrystalline silicon piece substandard products reworking method after the diffusion is characterized in that: may further comprise the steps:
(1) substandard products after will spreading are put into hydrofluoric acid solution and are soaked 4~10min, remove the phosphorosilicate glass layer that forms in the diffusion process, and wherein the volume ratio of hydrofluoric acid and water is 1:4~10 in the hydrofluoric acid solution;
(2) silicon chip after step (1) immersion is used washed with de-ionized water, remove the residual hydrofluoric acid of silicon chip surface;
(3) silicon chip after step (2) cleaning is put into NaOH solution and soak 2min~5min, wherein the mass percent concentration of NaOH solution is 2%~10%, and the temperature of NaOH solution is 60 ℃~80 ℃, to remove the surface diffusion layer of silicon;
(4) silicon chip after step (3) immersion is used H 2O 2Solution cleans up silicon chip, H 2O 2H in the solution 2O 2With the volume ratio of water be 1:4~10.
2. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method, it is characterized in that: the volume ratio of hydrofluoric acid and water is 1:5 in the step (1).
3. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method, it is characterized in that: the soak time in the step (1) is 6min.
4. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method, it is characterized in that: the mass concentration of NaOH solution is 5% in the step (3).
5. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method, it is characterized in that: the temperature of NaOH solution is 80 ℃ in the step (3).
6. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method, it is characterized in that: soak time is 2.5min in the step (3).
7. diffusion according to claim 1 back monocrystalline silicon piece substandard products reworking method is characterized in that: the H in the step (4) 2O 2With the volume ratio of water be 1:6.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102931290A (en) * 2012-11-27 2013-02-13 百力达太阳能股份有限公司 Polycrystalline silicon solar cell reworking method without damaging suede
CN105470108A (en) * 2015-09-28 2016-04-06 阳光大地(福建)新能源有限公司 Rework processing method of solar cell diffusion-blackened sheet
CN110518080A (en) * 2019-08-29 2019-11-29 无锡尚德太阳能电力有限公司 A kind of reworking method of acid making herbs into wool polycrystalline battery

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070042567A1 (en) * 2005-08-17 2007-02-22 Sakae Koyata Process for producing silicon wafer
CN101217173A (en) * 2008-01-10 2008-07-09 宁波杉杉尤利卡太阳能科技发展有限公司 A novel method of diffused layer removal on the single surface
CN102163549A (en) * 2011-01-27 2011-08-24 巨力新能源股份有限公司 Treating fluid for bad chip after crystalline silicon film coating and treating method thereof
CN102343352A (en) * 2010-07-26 2012-02-08 比亚迪股份有限公司 Recovery method for solar silicon slice

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070042567A1 (en) * 2005-08-17 2007-02-22 Sakae Koyata Process for producing silicon wafer
CN101217173A (en) * 2008-01-10 2008-07-09 宁波杉杉尤利卡太阳能科技发展有限公司 A novel method of diffused layer removal on the single surface
CN102343352A (en) * 2010-07-26 2012-02-08 比亚迪股份有限公司 Recovery method for solar silicon slice
CN102163549A (en) * 2011-01-27 2011-08-24 巨力新能源股份有限公司 Treating fluid for bad chip after crystalline silicon film coating and treating method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102931290A (en) * 2012-11-27 2013-02-13 百力达太阳能股份有限公司 Polycrystalline silicon solar cell reworking method without damaging suede
CN105470108A (en) * 2015-09-28 2016-04-06 阳光大地(福建)新能源有限公司 Rework processing method of solar cell diffusion-blackened sheet
CN110518080A (en) * 2019-08-29 2019-11-29 无锡尚德太阳能电力有限公司 A kind of reworking method of acid making herbs into wool polycrystalline battery

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Address after: No. 181-197, Shanshan Road, Wangchun Industrial Park, Haishu District, Ningbo City, Zhejiang Province, 315177

Patentee after: Ningbo Eureka solar energy Co., Ltd

Address before: 315177 Zhejiang city of Ningbo province Yinzhou District Wang Shanshan Lu Chun Industrial Park No. 181

Patentee before: NINGBO ULICA SOLAR TECHNOLOGY DEVELOPMENT Co.,Ltd.

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